The invention relates to an electrical switch in which a common contact body and a first selective contact body and a second selective contact body are provided in a housing. A movable contactor that can be moved outside of the housing against spring force produces the electrically conducting connection between the common contact body and either the first or the second selective contact body. A switch of this type is known for instance from DE 44 20 665 B4.
In this known switch, the contact surfaces of the first selective contact body and of the second selective contact body are set in a wall of the switch housing. The contactor is a sliding body that is provided with an actuating member that projects from the housing. Added to the sliding body is a contact plate that has a projecting contact finger. The contactor is pressed into its final position by a compression spring in the form of a helical spring. The helical spring produces the electrically conducting connection between the contact finger and the common contact body set in the housing. In the first final position, effected by the helical spring, the contact finger located on the contactor is positioned against the contact surface of the first selective contact body. When there is pressure on the actuating member, the contactor is displaced against the restoring force of the helical spring into its second final position in which the contact finger is positioned against the contact surface of the second selective contact body.
Switches of this type are embodied in the fields of miniaturization and subminiaturization and perform switching tasks in which a normally closed electrical contact is temporarily interrupted by the mechanical effect on the actuating member and the conducting connection is produced on a normally closed second contact.
Switches of this type are particularly suitable for position detection tasks in automatic production processes. However, typical areas of application can also be lock systems in vehicle bodies and interior areas of a motor vehicle as well as various position queries in household devices or other mechanisms.
Given that in the known switch in accordance with DE 44 20 665 B4 the contact finger of the contactor slidingly alternates from contacting the first contact surface to contacting the second contact surface, what is achieved is that the switching behavior can be intentionally influenced. The influencing variables are primarily the slide path of the contact finger, the size of the contact surfaces, and their distance from one another. These variables can be optimized with respect to one another. For instance, it is possible to maintain a strict separation between both switching positions, or to prevent an intermediate position in which both contact surfaces are in conducting contact with the contact finger. Furthermore, what a switch of this type achieves is that the switching process reliably occurs at a desired point in time regardless by whether the actuation from outside occurs rapidly or slowly.
In the known switch in accordance with DE 44 20 665 B4, it is disadvantageous that the current-conducting connection requires a plurality of components starting from the fixed common contact body via the helical spring and the contact plate up to the contact finger and in addition requires the sliding body of the contactor for holding or positioning these components. Moreover, a narrow side of the plate-like body of the contactor must be guided very precisely along the flat housing wall in which the contact surfaces of the first and second selective contact bodies are set. The contactor must not jam or become canted. This requires extremely precise manufacture of the individual parts and complex assembly if reliable functioning is to be assured over extended periods of time.
Known from EP 1 533 823 A1 is another switch in which a common contact body is selectively connected to a first or a second selective contact body using a contactor. In this case, the contactor is an elastically deformable leaf spring that receives from a tongue formed by it a pre-tension in the longitudinal direction and that is therefore urged to assume a curved shape. With the entire width of its free end the leaf-shaped contactor engages in the intermediate space of correspondingly formed areas of the selective contact body. The surfaces of these areas run parallel to the surface of the leaf-shaped contactor. The electrically conducting connection between the contactor and one of the two selective contact bodies can be produced using additional small contact bodies that are disposed at the free end of the leaf-shaped contactor and at the aforesaid areas of the first and second selective contact bodies. The surface of the leaf-shaped contactor and the surfaces of the aforesaid areas on the selective contactors run parallel to one another. The switching state is changed in that an actuating member acts on the opposing free end of the leaf-shaped contactor. The actuating member is acted upon by a compression spring, exerting a tensile force on the end of the leaf spring opposing the switching area. The leaf-shaped contactor obtains an extended shape from the tensile force. When the actuating member is depressed, the leaf-shaped contactor relaxes under the effect of its internal tension, transitions to its curved shape, and thus moves into the opposing switching position in which it is connected, electrically conducting, to the second selective contact body. The switch in accordance with EP 1 533 823 A1 is thus a so-called “sensitive switch” that has other switching properties than the earlier aforesaid switch in accordance with DE 44 20 665 B4. Above all it is not possible to precisely adjust the switching function with the switch in accordance with EP 1 533 823 A1 as it was described in the foregoing. In addition, the aforesaid special switching bodies must be placed on the switching free end of the elastically deformable contactor in accordance with EP 1 533 823 A1, likewise on the surfaces of the opposing areas of first and second selective contactor, which surfaces cooperate therewith; otherwise it is not possible to produce a reliable electrical contact.
The underlying object of the invention is therefore to create an electrical switch in which during a switching procedure the switching behavior can be precisely adjusted regardless of the type of operation and which also enables an intermediate position with contact to both selective contact bodies and which still enables reliable operation over extended periods of time with a simple structure, simple production, and simple assembly.